1. Field
The following description relates to a negative active material, a negative electrode including the same, and a lithium battery including the negative electrode.
2. Description of the Related Art
Lithium secondary batteries used in portable electronic devices for information communication, such as personal data assistants (PDAs), mobile phones, and laptop computers, electric bicycles, electric vehicles, and the like, have a higher discharge voltage that is about twice or more than existing batteries, and thus exhibit a high energy density.
A lithium battery includes a positive electrode and a negative electrode, each including an active material that allows intercalation and deintercalation of lithium ions, and an organic electrolyte or a polymer electrolyte filling the gap between the negative and positive electrodes. Lithium batteries produce electrical energy from redox reactions that take place as lithium ions are intercalated into or deintercalated from the positive electrode and negative electrode.
Lithium-transition metal oxides, such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or lithium nickel cobalt manganese oxide (Li[NiCoMn]O2, Li[Ni1-x-yCoxMy]O2), having a structure for allowing intercalation of lithium ions may be used as positive active materials for lithium secondary batteries.
Carbonaceous materials in various forms, such as artificial graphite, natural graphite or hard carbon, which allow intercalation and deintercalation of lithium ions, and non-carbonaceous materials, such as silicon (Si), have been studied for use as negative electrode active materials.
Such non-carbonaceous materials exhibit a capacitance density ten times or greater than that of graphite. However, poor electrical conductivity of non-carbonaceous materials and the volumetric expansion and shrinkage during charging and discharging of the lithium secondary battery may deteriorate the capacity retention rate, charge/discharge efficiency, and lifetime characteristics of a battery using the non-carbonaceous materials.
Therefore, there is a desire for the development of high-performance negative active materials with improved electrical conductivity and improved cycle lifetime characteristics.